Polyamides derived from polymeric fatty acids, such as dimer acid, are well known and are highly useful adhesives for numerous applications with a wide variety of substrates. For example, polyamides derived from polymeric fatty acids and piperazine or dipiperidyl type diamines, and which optionally contain other dibasic acids or diamines, are described in U.S. Pat. No. 3,377,303. These polyamide resins are useful for hot melt bonding vinyl substrates. U.S. Pat. No. 3,738,950 discloses adipic acid modified polyamide resins derived from polymeric fatty acids and piperazine.
Where maximum vinyl adhesion is desired it is generally considered advantageous to incorporate as high a level of piperazine as possible in the polyamide without detracting from the other desirable characteristics of the resin. The weight percentage of piperazine present in polymeric fatty acid derived polyamides, however, is significantly less than it could be if it were possible to employ short-chain dibasic acids in place of all or a large portion of the polymeric fatty acid. It would be highly desirable therefore to prepare piperazine-containing thermoplastic polyamide resins which are not derived from polymeric fatty acids but which exhibit good overall characteristics making them suitable for hot melt bonding of various substrates. It would be even more advantageous if such resins contained larger than usual amounts of piperazine so that improved vinyl adhesion was obtained.
Ether diamines are also known to be useful reactants for the preparation of polyamides. U.S. Pat. No. 3,882,090 discloses water-soluble polyamides derived from an aliphatic diamine containing ether linkages and low molecular weight dicarboxylic acids which are useful as textile sizing agents, coatings and adhesives. British Pat. No. 1,319,807, for example, discloses copolyamide resins derived from polymeric fatty acids and low molecular weight aliphatic ether diamines. Similarly, U.S. Pat. No. 3,499,853 discloses thermoplastic adhesives derived from relatively low molecular weight ether diamines, by themselves or in combination with ethylene diamine, and polymeric fatty acids. More recently, the reaction of aliphatic ether diamines with short-chain aliphatic dicarboxylic acids has been shown. German Offenlengungsschrift 25 52 518 discloses thermoplastic adhesive compositions derived from a polyoxypropylene polyamine and an aliphatic or aromatic dicarboxylic acid having from 4 to 20 carbon atoms. German Offenlegungsschrift 25 52 455 further describes thermoplastic polyamide compositions which additionally contain piperazine with the polyoxypropylene polyamine and aliphatic or aromatic dicarboxylic acid and indicates these resins are useful adhesives particularly with epoxy materials.